Printed circuit, backlight unit and display device

ABSTRACT

Embodiments of the present disclosure relate to a printed circuit, a backlight unit, and a display device. The printed circuit on which a light source is mounted can be easily manufactured in a single form, by depositing and arranging a wiring layer on a substrate and mounting the light source on the wiring layer. Further, the printed circuit is arranged so that the wiring layer includes a plurality of bonding metal layers and a plurality of wiring metal layers, and a part of the bonding metal layer positioned between the plurality of wiring metal layers and disposed in an area overlapping a pad portion of the light source is removed. Therefore, even though the main metal layer of the wiring layer is removed during reworking, it is possible to provide the printed circuit capable of electrically connecting to the light source by the sub-metal layer of the wiring layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No.10-2020-0139659, filed on Oct. 26, 2020, which is hereby incorporated byreference for all purposes as if fully set forth herein.

BACKGROUND Field

The present disclosure relates to a printed circuit, a backlight unitand a display device.

Description of Related Art

Along with the recent advent of the information society, the demand fordisplay devices for displaying images is ever increasing, and varioustypes of display devices such as e.g., a liquid crystal display deviceand an organic light emitting display device are utilized.

Such a liquid crystal display device may include a display panel havinga liquid crystal layer, and a backlight unit for supplying light to thedisplay panel.

The backlight unit may include a plurality of light sources and variousoptical members for efficiently supplying light emitted from the lightsources to the display panel. The plurality of light sources may beincluded in the backlight unit with a form of being mounted on a printedcircuit, for example.

At this juncture, any defect may occur in the process of mounting thelight source onto the printed circuit. As such, in case where adefective mounting of the light source is caused, it will naturally leadto difficulties in replacing the printed circuit itself or performingthe entire manufacturing process of the printed circuit again, due tothe difficulty of rework.

SUMMARY

Various embodiments of the present disclosure provide a method foreasily manufacturing a printed circuit on which a light source includedin a backlight unit is mounted.

Various embodiments of the present disclosure provide a method forremoving any defective light source and then mounting the light sourceagain on the printed circuit through a rework, when any defect occurs inthe process of mounting the light source on the printed circuit.

In one aspect, embodiments of the present disclosure provide a backlightunit including a plurality of light sources and a printed circuit onwhich the plurality of light sources are mounted and including one ormore wiring layers.

At least one of the one or more wiring layers included in the printedcircuit may include a main metal layer, a sub-metal layer disposedunderneath the main metal layer, and a bonding metal layer disposedbetween the main metal layer and the sub-metal layer, a portion of whichis removed in an area overlapping each of the plurality of lightsources.

The bonding metal layer may be located in some of the area overlappingeach of the plurality of light sources. Accordingly, in the areaoverlapping each of the plurality of light sources, a region in whichthe bonding metal layer is disposed and a region in which no bondingmetal layer is disposed may exist.

At least a portion of the main metal layer may be removed in the areaoverlapping at least one light source of the plurality of light sources.

A portion of the sub-metal layer located in the area overlapping thebonding metal layer in the area overlapping at least one light source ofthe plurality of light sources may be in an alloy state.

At least one light source of the plurality of light sources included inthe backlight unit may be in contact with the main metal layer, and atleast one other light source of the plurality of light sources may be incontact with the sub-metal layer.

Further, at least one light source of the plurality of light sourcesincluded in the backlight unit may be in contact with the bonding metallayer.

In another aspect, embodiments of the present disclosure provide adisplay device including the aforementioned backlight unit and a displaypanel positioned on the backlight unit and receiving light from thebacklight unit.

In still another aspect, embodiments of the present disclosure provide aprinted circuit including a substrate and one or more wiring layersdisposed on the substrate, at least one of the one or more wiring layersincluding a first bonding metal layer, a sub-metal layer disposed on thefirst bonding metal layer, a second bonding metal layer disposed on thesub-metal layer, and a main metal layer disposed on the second bondingmetal layer.

In the printed circuit, the first bonding metal layer may be entirelydisposed underneath the sub-metal layer, and the second bonding metallayer may be removed in some area between the main metal layer and thesub-metal layer.

According to embodiments of the present disclosure, a printed circuit onwhich a light source is mounted can be manufactured by means ofdepositing a wiring layer and a wiring insulating layer on a substrate,so that the light source can be efficiently mounted on the printedcircuit in a single formation despite an increased area of a displaypanel.

According to embodiments of the present disclosure, in an area where thelight source is mounted, the wiring layer included in the printedcircuit includes the main metal layer and the sub-metal layer, and it ispossible to dispose the bonding metal layer with its part removedbetween the main metal layer and the sub-metal layer. Accordingly, evenin case where a rework has to be performed due to a defective mountingof the light source, the light source may be electrically connected viathe sub-metal layer even if the main metal layer is removed.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the disclosurewill be more clearly understood from the following detailed description,taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram schematically showing the configuration of a displaydevice according to embodiments of the present disclosure.

FIG. 2 is a diagram illustrating an example of a cross-sectionalstructure of a backlight unit according to embodiments of the presentdisclosure.

FIG. 3 is a diagram illustrating an example of a structure of a printedcircuit included in a backlight unit according to embodiments of thepresent disclosure.

FIGS. 4 to 6 are diagrams illustrating other examples of a structure ofa printed circuit included in a backlight unit according to embodimentsof the present disclosure.

FIG. 7 is a diagram illustrating an example of a structure of a wiringlayer included in a printed circuit according to embodiments of thepresent disclosure.

FIGS. 8 and 9 are diagrams illustrating examples of a process ofmounting a light source on a printed circuit in manufacturing abacklight unit according to embodiments of the present disclosure.

FIG. 10 is a diagram illustrating an example of a structure in which alight source is mounted on a printed circuit in a backlight unitaccording to embodiments of the present disclosure.

DETAILED DESCRIPTION

In the following description of examples or embodiments of the presentdisclosure, reference will be made to the accompanying drawings in whichit is shown by way of illustration specific examples or embodiments thatcan be implemented, and in which the same reference numerals and signscan be used to designate the same or like components even when they areshown in different accompanying drawings from one another. Further, inthe following description of examples or embodiments of the presentdisclosure, detailed descriptions of well-known functions and componentsincorporated herein will be omitted when it is determined that thedescription may make the subject matter in some embodiments of thepresent disclosure rather unclear. The terms such as “including”,“having”, “containing”, “constituting” “make up of”, and “formed of”used herein are generally intended to allow other components to be addedunless the terms are used with the term “only”. As used herein, singularforms are intended to include plural forms unless the context clearlyindicates otherwise.

Terms, such as “first”, “second”, “A”, “B”, “(A)”, or “(B)” may be usedherein to describe elements of the present disclosure. Each of theseterms is not used to define essence, order, sequence, or number ofelements etc., but is used merely to distinguish the correspondingelement from other elements.

When it is mentioned that a first element “is connected or coupled to”,“contacts or overlaps” etc. a second element, it should be interpretedthat, not only can the first element “be directly connected or coupledto” or “directly contact or overlap” the second element, but a thirdelement can also be “interposed” between the first and second elements,or the first and second elements can “be connected or coupled to”,“contact or overlap”, etc. each other via a fourth element. Here, thesecond element may be included in at least one of two or more elementsthat “are connected or coupled to”, “contact or overlap”, etc. eachother.

When time relative terms, such as “after,” “subsequent to,” “next,”“before,” and the like, are used to describe processes or operations ofelements or configurations, or flows or steps in operating, processing,manufacturing methods, these terms may be used to describenon-consecutive or non-sequential processes or operations unless theterm “directly” or “immediately” is used together.

In addition, when any dimensions, relative sizes etc. are mentioned, itshould be considered that numerical values for an elements or features,or corresponding information (e.g., level, range, etc.) include atolerance or error range that may be caused by various factors (e.g.,process factors, internal or external impact, noise, etc.) even when arelevant description is not specified. Further, the term “may” fullyencompasses all the meanings of the term “can”.

FIG. 1 is a diagram schematically showing the configuration of a displaydevice 100 according to embodiments of the present disclosure.

Referring now to FIG. 1 , the display device 100 may include a displaypanel 110, a gate driving circuit 120, a data driving circuit 130, acontroller 140 for driving the display panel 110, and the like.

The display panel 110 may include an active area AA in which a pluralityof subpixels SP are disposed, and a non-active area NA positionedoutside the active area AA.

In the display panel 110 may be disposed a plurality of gate lines GLand a plurality of data lines DL, and a subpixel SP may be arranged in aregion where the gate line GL and the data line DL intersect.

The gate driving circuit 120 may be controlled by the controller 140,and sequentially output a scan signal to the plurality of gate lines GLdisposed on the display panel 110 to control the driving timing of theplurality of sub-pixels SP.

The gate driving circuit 120 may include one or more gate driverintegrated circuits (GDIC) and may be located on either one side of thedisplay panel 110 or both sides of the display panel 110, depending uponits driving scheme.

Each gate driver integrated circuit may be connected to a bonding pad ofthe display panel 110 by a tape automated bonding (TAB) or achip-on-glass (COG) method, or may be implemented in a gate-in-panel(GIP) type to be disposed directly onto the display panel 110, or may beintegrated to be disposed on the display panel 110 as circumstancesdemand. Further, each gate driver integrated circuit may be implementedin a chip-on-film (COF) method for mounting on a film connected to thedisplay panel 110.

The data driving circuit 130 may receive image data from the controller140 and convert the image data into analog data voltages. In addition,the data voltage may be output to each data line DL according to atiming when a scan signal is applied via the gate line GL, so that eachsubpixel SP expresses brightness according to image data.

The data driving circuit 130 may include one or more source driverintegrated circuits (SDICs).

Each source driver integrated circuit (SDIC) may include a shiftregister, a latch circuit, a digital-to-analog converter, an outputbuffer, and the like.

A respective source driver integrated circuit (SDIC) may be connected toa bonding pad of the display panel 110 by means of a tape automatedbonding (TAB) or a chip-on-glass (COG) method, or directly disposed onthe display panel 110, or may be integrated and disposed on the displaypanel 110 as circumstances require. Further, the respective sourcedriver integrated circuit (SDIC) may be implemented in a chip-on-film(COF) method, in which case each source driver integrated circuit (SDIC)may be mounted on a film connected to the display panel 110 and thenelectrically connected to the display panel 110 through wiring on thefilm.

The controller 140 may supply various control signals to the gatedriving circuit 120 and the data driving circuit 130 in order to controlthe operations of the gate driving circuit 120 and the data drivingcircuit 130.

The controller 140 may be mounted on a printed circuit board, a flexibleprinted circuit or the like, and may be electrically connected to thegate driving circuit 120 and the data driving circuit 130 via theprinted circuit board, the flexible printed circuit, or the like.

The controller 140 may cause the gate driving circuit 120 to provide ascan signal according to the timing implemented in each frame, andconvert external received image data to the image data to be used by thedata driving circuit 130 and then deliver the converted image data tothe data driving circuit 130.

The controller 140 may receive various timing signals such as e.g., avertical synchronization signal (VSYNC), a horizontal synchronizationsignal (HSYNC), an input data enable signal (DE: Data Enable), and aclock signal (CLK), as well as the image data, from an outside system(e.g. a host system).

The controller 140 may generate various control signals using thevarious timing signals received from the outside system to provide themto the gate driving circuit 120 and the data driving circuit 130.

For example, the controller 140 may output various gate control signals(GCS) including a gate start pulse (GSP), a gate shift clock (GSC), agate output enable (GOE) signal and so on, in order to control the gatedriving circuit 120.

The gate start pulse (GSP) may serve to control the operation starttiming of one or more gate driver integrated circuits (GDIC) forming thegate driving circuit 120. The gate shift clock (GSC) is a clock signalcommonly input to one or more gate driver integrated circuits, and maycontrol the shift timing of the scan signal. The gate output enablesignal (GOE) may specify timing information of one or more gate driverintegrated circuits.

Further, in order to control the data driving circuit 130, thecontroller 140 may output various data control signals (DCS) including asource start pulse (SSP), a source sampling clock (SSC), a source outputenable (SOE) signal, and so on.

The source start pulse (SSP) may serve to control the data samplingstart timing of one or more source driver integrated circuits (SDIC)forming the data driving circuit 130. The source sampling clock (SSC) isa clock signal to control the sampling timing of data in each of thesource driver integrated circuits. The source output enable (SOE) signalmay control the output timing of the data driving circuit 130.

The display device 100 may further include a power management integratedcircuit for supplying various voltages or currents to the display panel110, the gate driving circuit 120, the data driving circuit 130, and soon, or for controlling various voltages or currents to be suppliedthereto.

A liquid crystal layer or a light emitting device may be disposed ineach of the plurality of subpixels SP, depending on the type of thedisplay device 100. For a liquid crystal display device with a liquidcrystal layer being disposed in the subpixel SP, the display device 100may include a backlight unit for supplying light to the display panel110.

FIG. 2 is a diagram illustrating an example of a cross-sectionalstructure of a backlight unit according to embodiments of the presentdisclosure.

Referring now to FIG. 2 , the backlight unit may include a plurality oflight sources 400 and various optical members.

The plurality of light sources 400 may be mounted on a printed circuit300.

The printed circuit 300, on which the light source 400 is mounted, andvarious optical members may be accommodated by a cover bottom 200.

The light source 400 may be, for example, a light emitting diode, suchas e.g., a mini-light emitting diode having a size of several hundredsof μm or a micro-light emitting diode having a size of several tens ofμm.

Each of the plurality of light sources 400 may include a light emittingsection 410 that emits light, and a pad section 420 connected to awiring supplying an electrical signal to the light source 400.

A reflective layer 500 may be disposed on at least a partial area of theprinted circuit 300 where no light source 400 is arranged.

The reflective layer 500, for example, may be in the form of a plate,and may include a plurality of holes LH positioned in regionscorresponding to each of the plurality of light sources 400. Thereflective layer 500 including the plurality of holes LH may be disposedon the printed circuit 300 on which the light source 400 is mounted.

When the size of the light source 400 is relatively small, the height ofthe upper end of the reflective layer 500 may be greater than the heightof the upper end of the light source 400.

Alternatively, in some cases, the reflective layer 500 may be disposedin a coated form on the uppermost surface of the printed circuit 300. Insuch a case, the height of the upper end of the reflective layer 500 maybe smaller than the height of the upper end of the light source 400.

When the light emitted from the light source 400 is scattered orreflected in a backward direction, the reflective layer 500 may causethe light reaching the reflective layer 500 to be reflected back towardthe display panel 110, so as to increase the efficiency of the light inthe backlight unit.

A light source protection unit 600 may be disposed on the light source400 and the reflective layer 500.

The light source protection unit 600 may be formed, for example, with aresin molding. Alternatively, it may be formed using an adhesivematerial such as e.g., optical clear adhesive (OCA), but is not limitedthereto.

The light source protection unit 600 may surround the light source 400,but in some cases, an air layer may exist in between the light source400 and the light source protection unit 600.

The light source protection unit 600 may protect the light source 400and perform a function of guiding the light emitted from the lightsource 400.

A light path control film 700 may be disposed on the light sourceprotection unit 600.

The light path control film 700 may include a base film 710 and aplurality of light path control patterns 720 disposed on at least onesurface of the base film 710.

The base film 700 may be made of a material having high transparency,and may be made of, for example, PC (Polycarbonate) or PET (PolyethyleneTerephthalate), but is not limited thereto.

Each of the plurality of light path control patterns 720 may be disposedin a region corresponding to each of the plurality of light sources 400.

The area of the light path control pattern 720 may be larger than thatof the light source 400, for example.

The area of the light path control pattern 720 may be the same as thearea of the hole LH included in the reflective layer 500, for example.

Alternatively, depending on the distance between the light source 400and the light path control pattern 720, the area of the light pathcontrol pattern 720 may be either larger or smaller than the area of thehole LH included in the reflective layer 500.

The light path control pattern 720 may be made of a material having highreflective properties, such as e.g., TiO2.

The light path control pattern 720 may cause part of the light emittedfrom the light source 400 to transmit, or cause most of the light toundergo reflection, diffraction, or scattering.

The light reflected by the light path control pattern 720 may bereflected back by the reflective layer 500. The light reflected by thereflective layer 500 may be emitted toward the display panel 110 in aregion between the light sources 400.

As such, the luminance uniformity of the backlight unit can be greatlyimproved by dispersing light in a region with a large amount of lightwhile increasing the light supplied to a region with a small amount oflight.

Various optical members may be disposed on the light path control film700, and for example, a color conversion sheet, a diffusion plate, aprism sheet, a diffusion sheet, and the like may be disposed.

According to the embodiments of the present disclosure, it is possibleto improve the uniformity of luminance and the light efficiencyrepresented by the backlight unit, even if the area of the display panel110 is increased due to the structure in which the light path controlfilm 700 is disposed over the light source 400.

Therefore, it is possible to improve the image quality represented bythe backlight unit while reducing the thickness of the backlight unit.

In the meantime, as the area of the display panel 110 increases,multiple printed circuits 300, on which the light sources 400 includedin the backlight unit are mounted, may be required. That is, due to thelimited size of the printed circuit 300, multiple printed circuits 300may be required to mount the light sources 400, thereby leading todifficulties in the manufacturing process.

Embodiments of the present disclosure provide a method for implementingthe printed circuit 300 for mounting the light sources 400 included inthe backlight unit, in a single form.

FIG. 3 is a diagram illustrating an example of the structure of aprinted circuit 300 included in a backlight unit according toembodiments of the present disclosure.

Referring now to FIG. 3 , the printed circuit 300 may include asubstrate 310 and at least one wiring layer 320 and 340 disposed on thesubstrate 310.

The substrate 310 may be made of, for example, glass, but is not limitedthereto.

A first wiring layer 320 may be deposited and disposed on the substrate310. The first wiring layer 320 may include at least one metal layer.

The first wiring layer 320 may be used for electrical connection betweenthe light source 400 and a circuit for driving the light source 400.

A wiring insulating layer 330 may be disposed on the first wiring layer320. The wiring insulating layer 330 may be formed of either OC(Overcoat) or PAC (Photo Acryl), but is not limited thereto.

A second wiring layer 340 may be disposed on the wiring insulating layer330.

The wiring insulating layer 330 may serve to insulate the first wiringlayer 320 and the second wiring layer 340 from each other.

The uppermost surface of the wiring insulating layer 330 may beplanarized to facilitate the arrangement of the second wiring layer 340.

The second wiring layer 340 may be deposited and may include at leastone metal layer. At least a portion of the metal layer included in thesecond wiring layer 340 may be the same as the metal layer included inthe first wiring layer 320.

The second wiring layer 340 may be used for electrical connectionbetween the light source 400 and the first wiring layer 320.

A first passivation layer 350 and a second passivation layer 360 may bedisposed on some area on the second wiring layer 340.

The first passivation layer 350 and the second passivation layer 360 maybe disposed in an area other than the area where the light source 400 isdisposed. The area in which the first passivation layer 350 is disposedand the area in which the second passivation layer 360 is disposed maybe the same or different from each other.

The first passivation layer 350 may be made of, for example, SiNx, butis not limited thereto. The second passivation layer 360 may be formedof, for example, a photo solder resist (PSR), but is not limitedthereto.

The first passivation layer 350 and the second passivation layer 360 mayserve to prevent corrosion of the second wiring layer 340. Further, thefirst passivation layer 350 and the second passivation layer 360 may beremoved from the area where the light source 400 is disposed, so thatthe second wiring layer 340 and the light source 400 may be electricallyconnected to each other.

The light source 400 may be mounted on the second wiring layer 340.

A portion of the wiring insulating layer 330 may be removed underneaththe light source 400.

A light leakage prevention layer 370 may be disposed in an area where aportion of the wiring insulating layer 330 is removed.

The light leakage prevention layer 370 may be the same as one of theinsulating materials disposed on the substrate 310, which material maybe opaque or have low transparency. For example, the light leakageprevention layer 370 may be made of the same material as the secondpassivation layer 360.

Alternatively, in some cases, the light leakage prevention layer 370 maybe made of the same material as the wiring insulating layer 330 whilebeing disposed with a thickness different from that of the wiringinsulating layer 330.

Alternatively, in some cases, the light leakage prevention layer 370 maybe made of an electrode material.

Thanks to the arrangement of the light leakage prevention layer 370, itwill be possible to prevent light from leaking downwardly of the lightsource 400 even though the substrate 310 is transparent.

As described above, the embodiments of the present disclosure canprovide a backlight unit having a structure in which the light source400 is mounted on a single type of printed circuit 300, since theprinted circuit 300 can be formed by means of depositing the wiringlayers 320 and 340 on the substrate 310.

Furthermore, the embodiments of the present disclosure make it possibleto implement the second wiring layer 340 contacting the light source 400with multiple metal layers, thereby facilitating reworking of the lightsource 400 when any failure occurs in mounting of the light source 400.

FIGS. 4 to 6 are views showing another example of the structure of theprinted circuit 300 included in the backlight unit according toembodiments of the present disclosure.

Referring first to FIG. 4 , the printed circuit 300 may include asubstrate 310 and at least one wiring layer 320 and/or 340 disposed onthe substrate 310. The substrate 310 may be made of a transparentmaterial, as in the above-described example.

A first wiring layer 320 may be disposed on the substrate 310.

The first wiring layer 320 may include a first bonding metal layer 321and a first wiring metal layer 322.

The first bonding metal layer 321 may be disposed on the substrate 310.The first bonding metal layer 321 may improve adhesiveness of the firstwiring metal layer 322.

The first bonding metal layer 321 may be made of, for example, Mo, Ti,or MoTi, but is not limited thereto.

The first wiring metal layer 322 may be disposed on the first bondingmetal layer 321.

The first wiring metal layer 322 may be formed to be thicker than thefirst bonding metal layer 321. The first wiring metal layer 322 may beelectrically connected to a pad part 420 of the light source 400 toserve as a wiring.

The first wiring metal layer 322 may be deemed as a “main metal layer”of the first wiring layer 320. The first wiring metal layer 322 may bemade of, e.g., Cu, but is not limited thereto.

A wiring insulating layer 330 may be disposed on the first wiring layer320.

A second wiring layer 340 may be disposed on the wiring insulating layer330. The second wiring layer 340 may be electrically connected to thefirst wiring layer 320 through a contact hole formed in the wiringinsulating layer 330.

The second wiring layer 340 may include a plurality of bonding metallayers 341 and 343 and a plurality of wiring metal layers 342 and 344.

The second wiring layer 340 may include, for example, a first bondingmetal layer 341, a first wiring metal layer 342, a second bonding metallayer 343, and a second wiring metal layer 344.

The first bonding metal layer 341 may be disposed on the wiringinsulating layer 330, to improve the adhesiveness of the first wiringmetal layer 342. The first bonding metal layer 341 may be made of, e.g.,Mo, Ti, or MoTi, but is not limited thereto.

A first wiring metal layer 342 may be disposed on the first bondingmetal layer 341. The first wiring metal layer 342 may be disposed to bethicker than the first bonding metal layer 341. The first wiring metallayer 342 may be made of, e.g., Cu, but is not limited thereto.

The first wiring metal layer 342 may be deemed as a “sub-metal layer”.

A second bonding metal layer 343 may be disposed on the first wiringmetal layer 342.

The second bonding metal layer 343 may be made of the same material asthe first bonding metal layer 341. The second bonding metal layer 343may be disposed to have a thickness similar to that of the first bondingmetal layer 341.

The second bonding metal layer 343 may improve the adhesiveness of thesecond wiring metal layer 344 disposed on the second bonding metal layer343.

The second wiring metal layer 344 may be disposed on the second bondingmetal layer 343 and may be made of the same material as the first wiringmetal layer 342. The second wiring metal layer 344 may be thicker thanthe second bonding metal layer 343.

The second wiring metal layer 344 may be deemed as a “main metal layer”.

A first passivation layer 350 and a second passivation layer 360 may bedisposed on the second wiring metal layer 344.

On the second wiring metal layer 344, the light source 400 may bemounted in an area where the first passivation layer 350 and the secondpassivation layer 360 are not disposed.

The light source 400 may be electrically connected to the second wiringmetal layer 344. Further, an electrical signal for driving the lightsource 400 may be supplied via the first wiring layer 320 and the secondwiring layer 340.

As the second wiring layer 340 includes a plurality of wiring metallayers 342 and 344, the plurality of wiring metal layers 342 and 344 maybe disposed in an area overlapping the light source 400.

Here, the area overlapping the light source 400 may indicate an area inwhich the pad part 420 of the light source 400 is disposed.

The second wiring metal layer 344 of the second wiring layer 340 locatedin the area overlapping the light source 400 may be electricallyconnected to the pad part 420 of the light source 400. Accordingly, thesecond wiring metal layer 344 may serve as a “main metal layer”.

When reworking of the light source 400 disposed on the second wiringmetal layer 344 is required, at least a portion of the second wiringmetal layer 344 may be removed by means of removing the light source400.

The first wiring metal layer 342 positioned underneath the second wiringmetal layer 344 is exposed to be electrically connected to the lightsource 400. That is, the first wiring metal layer 342 may serve as a“sub-metal layer”.

To this end, in the area overlapping the light source 400, a portion ofthe second bonding metal layer 343 is removed so that the first wiringmetal layer 342 of the second wiring layer 340 can be exposed during thereworking.

Then, in an area that does not overlap the light source 400, the secondbonding metal layer 343 may be entirely disposed in order to improveadhesiveness between the first wiring metal layer 342 and the secondwiring metal layer 344 included in the second wiring layer 340.

Further, the first bonding metal layer 341 positioned under the firstwiring metal layer 342 may be entirely disposed between the wiringinsulating layer 330 and the first wiring metal layer 342.

In other words, the first bonding metal layer 341 may be entirelydisposed to improve adhesiveness, and the second bonding metal layer 343may be partially disposed with its part being removed to expose thefirst wiring metal layer 342 during reworking while improvingadhesiveness.

When the second bonding metal layer 343 is entirely removed from thearea overlapping the light source 400, the first wiring metal layer 342may be removed together with the second wiring metal layer 344 when thelight source 400 is removed for reworking.

Accordingly, a portion of the second bonding metal layer 343 may beremoved in the area overlapping the light source 400, while otherportion may remain.

For example, the second bonding metal layer 343 may be removed in anarea corresponding to 50% of the area overlapping the light source 400,while the second bonding metal layer 343 may remain in an areacorresponding to its remaining 50%.

Further, in order to prevent removal of the first wiring metal layer 342during the rework, the ratio of the area from which the second bondingmetal layer 343 is removed may be less than a certain level (e.g., nomore than 60%).

Further, a portion from which the second bonding metal layer 343 isremoved in the area overlapping the light source 400 may be divided intoseveral parts.

Increasing the area from which the second bonding metal layer 343 isremoved to facilitate electrical connection between the light source 400and the first wiring metal layer 342 during the rework, and arrangingthe second bonding metal layer 343 to be divided in a fixed pattern,will make it possible to prevent the first wiring metal layer 342 frombeing removed when the light source 400 is removed.

In addition, when at least one element other than the light source 400is disposed on the second wiring layer 340, a portion of the secondbonding metal layer 343 may be removed from an area overlapping the areawhere the at least one element is disposed.

Accordingly, the second wiring metal layer 344 may function as a “mainmetal layer” in the area where the corresponding element is disposed,and the first wiring metal layer 342 may function as a “sub-metallayer”, so that the rework of the light source 400 as well as theelement disposed on the second wiring layer 340 can be easily performed.

Furthermore, the embodiments of the present disclosure provide a methodcapable of performing reworking of elements electrically connected onthe first wiring layer 320, by causing the first wiring layer 320positioned underneath the wiring insulating layer 330 to include aplurality of wiring metal layers 321 and 323.

Referring then to FIG. 5 , the first wiring layer 320 disposed on thesubstrate 310 may include a plurality of bonding metal layers 321 and323 and a plurality of wiring metal layers 322 and 324.

The first wiring layer 320 may include, for example, a first bondingmetal layer 321, a first wiring metal layer 322, a second bonding metallayer 323, and a second wiring metal layer 324.

A wiring insulating layer 330 may be disposed on the first wiring layer320, and a second wiring layer 340 including a plurality of wiring metallayers 342 and 344 may be disposed on the wiring insulating layer 330.

At least one circuit element 800 may be disposed in an area where thewiring insulating layer 330 is not disposed on the first wiring layer320. This circuit element 800 may be a circuit for driving the lightsource 400 or may indicate a connector portion to which the circuit isconnected. That is, it may refer to any types of circuit elements thatmay be mounted on the first wiring layer 320.

A portion of the second bonding metal layer 323 may be removed from thearea overlapping the circuit element 800 disposed on the first wiringlayer 320. Further, another portion of the second bonding metal layer323 may remain in the area overlapping the circuit element 800.

Hence, when performing a rework of the circuit element 800 disposed onthe first wiring layer 320, the first wiring metal layer 322 may beexposed through the area where the second bonding metal layer 323 isremoved even if the second wiring metal layer 324 is removed. Then, thecircuit element 800 may be electrically connected to the first wiringmetal layer 322, so that the reworking of the circuit element 800 can becarried out.

As described above, the embodiments of the present disclosure make itpossible to facilitate reworking of the light source 400 or the circuitelement 800 mounted on the wiring layers 320 and 340, by depositing atleast one wiring layer 320 or 340 on the substrate 310 to form theprinted circuit 300 and forming each of the wiring layers 320 and 340 inmultiple layers.

Further, in the area where the light source 400 or the circuit element800 is not mounted, in other words, in at least a portion of the regionwhere no reworking is required, the layers forming the wiring layers 320and 340 may be different.

Referring then to FIG. 6 , on a substrate 310 may be disposed a firstwiring layer 320, a wiring insulating layer 330, and a second wiringlayer 340.

The first wiring layer 320 may include a plurality of bonding metallayers 321 and 323 and a plurality of wiring metal layers 322 and 324.

The second wiring layer 340 may include a plurality of bonding metallayers 341 and 343 and a plurality of wiring metal layers 342 and 344.

Here, the first wiring layer 320 disposed underneath the wiringinsulating layer 330 may have a single bonding metal layer 321 and asingle wiring metal layer 322.

Because a region where the first wiring layer 320 is located under thewiring insulating layer 330 is not the region on which the light source400 or the circuit element 800 is mounted, only the bonding metal layer321 and the first wiring metal layer 322 may be disposed.

Further, the first wiring metal layer 322 and the second wiring metallayer 324 may be disposed in an area where the wiring insulating layer330 is not disposed and the circuit element 800 is to be mounted.

The second wiring layer 340 disposed on the wiring insulating layer 330may be also arranged such that only the bonding metal layer 321 and thefirst wiring metal layer 342 may be disposed in some area where thelight source 400 is not mounted, as circumstances require.

Embodiments of the present disclosure can provide a printed circuit 300capable of reworking by means of arranging at least one of the wiringlayers 320 and 340 disposed on the substrate 310 in multiple layers.

In addition, the embodiments of the present disclosure can provide aprinted circuit 300 in which a sub-metal layer is exposed without beingremoved during the reworking, capable of being electrically connected tothe light source 400 and so, by patterning and arranging a portion ofthe bonding metal layer positioned between the main metal layer and thesub-metal layer, in an area overlapping the light source 400 and thecircuit element 800.

FIG. 7 is a diagram illustrating an example of the structure of a wiringlayer included in the printed circuit 300 according to embodiments ofthe present disclosure, and in particular, shows an example of thestructure of the second wiring layer 340. In addition, the first bondingmetal layer 341 and the second bonding metal layer 343 may be made ofe.g., MoTi, and the first wiring metal layer 342 and the second wiringmetal layer 344 may be made of e.g., Cu.

Referring now to FIG. 7 , for example, as in Case 1, the first wiringmetal layer 342 and the second bonding metal layer 343 may be disposedon the first bonding metal layer 341. Further, a portion of the secondbonding metal layer 343 may be patterned and removed.

Here, only the second bonding metal layer 343 may be removed while thefirst wiring metal layer 342 may not be removed.

The second wiring metal layer 344 may be disposed with a portion of thesecond bonding metal layer 343 being removed.

As such, the second wiring metal layer 344 and the first wiring metallayer 342 may be arranged in a coupled form. Further, when the secondwiring metal layer 344 is removed during the reworking, the first wiringmetal layer 342 may be exposed to provide a structure capable ofelectrically connecting to the light source 400 and the like.

As another example, as in Case 2, the first wiring metal layer 342 andthe second bonding metal layer 343 may be disposed on the first bondingmetal layer 341. When the second bonding metal layer 343 is patternedand removed, at least a portion of the first wiring metal layer 342 maybe removed.

The second wiring metal layer 344 may be disposed on the second bondingmetal layer 343, and a portion of the second wiring metal layer 344 maybe disposed up to a region where the first wiring metal layer 342 isremoved.

The second wiring metal layer 344 and the first wiring metal layer 342may be disposed in a coupled form, and the first wiring metal layer 342may be exposed during the reworking, so as to provide an electricalconnection to the light source 400 and so on.

FIGS. 8 and 9 are diagrams illustrating an example of mounting the lightsource 400 on the printed circuit 300 in the process of manufacturingthe backlight unit according to embodiments of the present disclosure.

Referring now to FIGS. 8 and 9 , an example of a process of mounting thelight source 400 on the second wiring layer 340 and performing therework of the mounted light source 400 is shown.

Referring to a step {circle around (a)} of FIG. 8 , an anti-oxidationlayer 900 may be disposed on the second wiring layer 340. A solder 1000and a light source 400 may be then disposed on the anti-oxidation layer900, so that a surface mount technology (SMT) can be carried out.

At this juncture, a portion of the second bonding metal layer 343 may beremoved from the second wiring layer 340 positioned in the region wherethe light source 400 is mounted.

As the SMT progresses, for example, Sn included in the solder 1000 maydiffuse, and Cu included in the second wiring layer 340 may diffuse.

As reflow proceeds, as shown in a step {circle around (b)} of FIG. 8 , aportion of the solder 1000 and the wiring metal layers 342 and 344 ofthe second wiring layer 340 form an alloy, so that the light source 400can be fixed onto the second wiring layer 340.

The second wiring metal layer 344 positioned in the upper portion of thesecond wiring layer 340 may be in an alloy state.

Further, a portion of the first wiring metal layer 342 located in anarea overlapping the area where the second bonding metal layer 343 isremoved in the lower portion of the second wiring layer 340 may be in analloy state.

In this way, with the light source 400 being mounted, the light source400 may be removed as such a rework is required.

Referring then to a step {circle around (c)} of FIG. 8 , as the lightsource 400 is removed, only a portion disposed on the second bondingmetal layer 343 of the alloy-formed portion may be removed. Further, ascircumstances require, some of the alloy-formed portion may remain onthe second bonding metal layer 343.

As seen in the example shown in FIG. 8 , the first wiring metal layer342 located underneath the second bonding metal layer 343 may remaineven if the alloy-formed portion of the second wiring metal layer 344located on the second bonding metal layer 343 is removed.

Then, an electrical connection to the light source 400 may be made usingthe first wiring metal layer 342, so that the light source 400 can bereworked.

Referring then to a step {circle around (d)} of FIG. 9 , once the layerpositioned on the second bonding metal layer 343 has been removed, thesolder 1000 and the light source 400 may be disposed to perform the SMT.

As the SMT progresses, Sn in the solder 1000 may diffuse, and Cuincluded in the second wiring layer 340 may diffuse.

As such, as seen in the example shown in a step {circle around (e)} ofFIG. 9 , a portion of the solder 1000 and a portion of the first wiringmetal layer 341 form an alloy state, thereby causing the light source400 to be electrically connected to the second wiring layer 340.

Here, as the reflow proceeds while a portion of the first wiring metallayer 342 has been into an alloy state in the process prior to therework, a region in which an alloy is formed by diffusion may beexpanded.

For example, if a width of the portion where the alloy is formed in thefirst wiring metal layer 342 prior to the rework is W1, then a width ofthe portion where the alloy is formed in the first wiring metal layer342 after the rework will be W2, which may be greater than W1.

At least a portion of the first wiring metal layer 342 positionedunderneath the area overlapping the second bonding metal layer 343 maybe in an alloy state by the rework process.

As described above, the alloy can be formed by diffusion, so that anelectrical connection to the light source 400 may be formed via thefirst wiring metal layer 342 positioned under the second bonding metallayer 343.

According to the embodiments of the present disclosure, the secondwiring layer 340 includes a plurality of wiring metal layers 342 and344, and a portion of the second bonding metal layer 343 positionedbetween the plurality of wiring metal layers 342 and 344 is removed,thereby enabling the first wiring metal layer 342 positioned underneaththe second bonding metal layer 343 to perform a function of a wiring forsupplying a signal to the light source 400, during a rework.

In other words, when no rework is performed, the second wiring metallayer 344 positioned in the upper portion of the second wiring layer 340may serve as a wiring, while when the rework is performed, the firstwiring metal layer 342 disposed in the lower portion of the secondwiring layer 340 may serve as a wiring.

Accordingly, a portion of the plurality of light sources 400 mounted onthe printed circuit 300 may be in contact with the second wiring metallayer 344 of the second wiring layer 340, while other portion may be incontact with the first wiring metal layer 342 thereof.

FIG. 10 is a diagram illustrating an example of a structure in which alight source 400 is mounted on a printed circuit 300 in a backlight unitaccording to embodiments of the present disclosure.

Referring now to FIG. 10 , the light source 400 located on the left sideof the light sources 400 mounted on the printed circuit 300 shows a casethat it is mounted with no rework performed. Further, the light source400 located on the right side thereof shows a case that it is mountedwith the rework performed.

When no rework is performed, the light source 400 may contact the secondwiring metal layer 344 of the second wiring layer 340 to form anelectrical connection.

When the rework is performed, the light source 400 may contact the firstwiring metal layer 342 of the second wiring layer 340 to form anelectrical connection. Likewise, the light source 400 may contact thesecond bonding metal layer 343 positioned on the first wiring metallayer 342.

Alternatively, as circumstances demand, a portion of the second wiringmetal layer 344 may remain on the second bonding metal layer 343, evenwhen the rework is performed. In such a case, the light source 400 maybe disposed abutting on the second wiring metal layer 344, but it may bedisposed at a lower position than when no rework is performed.

According to the above-described embodiments of the present disclosure,the printed circuit 300 on which the light source 400 is mounted can beeasily manufactured in one simple form, by manufacturing the printedcircuit 300 by means of the process of depositing the wiring layers 320and 340 on the substrate 310.

Further, it is possible to provide the printed circuit 300 in which therework of the light source 400 or the circuit element 800 mounted on theprinted circuit 300 can be easily performed, by forming at least aportion of the wiring layers 320 and 340 included in the printed circuit300 in multiple layers.

Accordingly, it is possible to improve the efficiency of the process ofmounting the light source 400 on the printed circuit 300 included in thebacklight unit, thereby enhancing the production yield.

The above description has been presented to enable any person skilled inthe art to make and use the technical idea of the present disclosure,and has been provided in the context of a particular application and itsrequirements. Various modifications, additions and substitutions to thedescribed embodiments will be readily apparent to those skilled in theart, and the general principles defined herein may be applied to otherembodiments and applications without departing from the spirit and scopeof the present disclosure. The above description and the accompanyingdrawings provide an example of the technical idea of the presentdisclosure for illustrative purposes only. That is, the disclosedembodiments are intended to illustrate the scope of the technical ideaof the present disclosure. Thus, the scope of the present disclosure isnot limited to the embodiments shown, but is to be accorded the widestscope consistent with the claims. The scope of protection of the presentdisclosure should be construed based on the following claims, and alltechnical ideas within the scope of equivalents thereof should beconstrued as being included within the scope of the present disclosure.

What is claimed is:
 1. A display device, comprising: a display panel;and a backlight unit supplying light to the display panel, wherein thebacklight unit comprises: a plurality of light sources; and a printedcircuit on which the plurality of light sources are mounted, andincluding one or more wiring layers; wherein at least one of the one ormore wiring layers comprises: a main metal layer; a sub-metal layerdisposed underneath the main metal layer; and a bonding metal layerdisposed between the main metal layer and the sub-metal layer, a portionof which is removed in an area overlapping each of the plurality oflight sources.
 2. The display device of claim 1, wherein the bondingmetal layer is disposed in a portion of the area overlapping each of theplurality of light sources.
 3. The display device of claim 1, wherein atleast a portion of the main metal layer is removed in the areaoverlapping at least one light source of the plurality of light sources.4. The display device of claim 1, wherein a portion of the sub-metallayer located in an area overlapping the bonding metal layer in the areaoverlapping at least one light source of the plurality of light sourcesis in an alloy state.
 5. The display device of claim 1, wherein at leasta portion of the main metal layer in the area overlapping at least onelight source of the plurality of light sources is in an alloy state. 6.The display device of claim 5, wherein at least a portion of thesub-metal metal layer located in an area overlapping the area in whichthe bonding metal layer is removed in the area overlapping at least onelight source of the plurality of light sources is in an alloy state. 7.The display device of claim 1, wherein at least one light source of theplurality of light sources is in contact with the main metal layer, andat least one other light source of the plurality of light sources is incontact with the sub-metal layer.
 8. The display device of claim 1,wherein at least one light source of the plurality of light sources isin contact with the bonding metal layer.
 9. The display device of claim1, wherein there are a plurality of areas with the bonding metal layerbeing removed in the area overlapping each of the plurality of lightsources, and the plurality of areas are spaced apart from each other.10. The display device of claim 1, wherein the main metal layer and thesub-metal layer are made of the same material, and the main metal layerand the sub-metal layer are made of a material different from thebonding metal layer.
 11. The display device of claim 1, wherein athickness of the main metal layer and a thickness of the sub-metal layerare greater than a thickness of the bonding metal layer.
 12. The displaydevice of claim 1, further comprising at least one circuit elementlocated in an area other than the area overlapping the plurality oflight sources, and being mounted on the wiring layer, wherein a portionof the bonding metal layer is removed from an area overlapping the atleast one circuit element.
 13. The display device of claim 1, whereinthe printed circuit comprises: a substrate; a first wiring layerdisposed on the substrate; a wiring insulating layer disposed on thefirst wiring layer; and a second wiring layer disposed on the wiringinsulating layer; wherein at least one of the first wiring layer and thesecond wiring layer comprises the main metal layer and the sub-metallayer.
 14. The display device of claim 13, wherein the first wiringlayer comprises the main metal layer and the sub-metal layer, and themain metal layer of the first wiring layer is disposed in an area otherthan the area in which the wiring insulating layer is disposed.
 15. Thedisplay device of claim 14, wherein a portion of the sub-metal layer ofthe first wiring layer is disposed underneath the wiring insulatinglayer and is electrically connected to the second wiring layer.
 16. Abacklight unit, comprising: a plurality of light sources; and a printedcircuit on which the plurality of light sources are mounted, andincluding one or more wiring layers; wherein at least one of the one ormore wiring layers comprises: a main metal layer; a sub-metal layerdisposed underneath the main metal layer; and a bonding metal layerdisposed between the main metal layer and the sub-metal layer, a portionof which is removed in an area overlapping each of the plurality oflight sources.
 17. A printed circuit comprising: a substrate; and one ormore wiring layers disposed on the substrate; wherein at least one ofthe one or more wiring layers comprises; a first bonding metal layer; asub-metal layer disposed on the first bonding metal layer; a secondbonding metal layer disposed on the sub-metal layer; and a main metallayer disposed on the second bonding metal layer, wherein the firstbonding metal layer is entirely disposed underneath the sub-metal layer,and the second bonding metal layer is removed from a partial areabetween the main metal layer and the sub-metal layer.